Multiple motor system



April 955" J. M; PESTARINI 2,636,152

MULTIPLE MOTOR SYSTEM Filed Sept. 21, 1946 2 SHEETS-SHEET l INVENTOR Jose v12 MPesLarz'ni E 1Z5. W

April 1953 J. PESTARINI 2,636,152

MULTIPLE MOTOR SYSTEM Filed Sept. 21, 1946 2 SHEETS-SHEET 2 CONSUMER 7 INVENTOR F I G 7 Jsepiz Mfiestarini BY 11%;.W

TTORNEY Patented Apr. 21, 1953 UNITED STATES PATENT OFFICE MULTIPLE MOTOR SYSTEM Joseph Maximus Pestarini, Staten Island, N. Y. Application September 21, 194e, Serial No. 698,494

6 Claims. (Cl. 318-140) This invention relates to a system comprisin a plurality of electric motors operating at voltages maintaining a constant ratio.

There are many situations where a plurality of electric motors must operate under the same difference of potential and yet they must absorb currents which must be maintained at a given ratio.

The motors considered here may be connected in parallel to the same terminals or they may be submitted to the same difierence of potential and yet be connected to different terminals. The latter case occurs when the said motors are energized by a single metadyne but are inserted in different loops of the said metadyne.

In conventional multiple motor systems energized by the same difference of potential, a slight difierence of the counter electromotive force induced in the motors results in a large and injurious discrepancy in the intensity of current. Accordingly an object of this invention is to provide a multiple motor system wherein each motor absorbs practically the desired value of current independently of large difierences in construction and in conditions of operations of the motors. A further object of the invention is to reduce the weight of conductors in the motorwindings and the sizes of the switchgear controlling the operation of the system.

The invention consists essentially in means for creating in each motor a corrective exciting flux which adjusts the counter electromotive force at the necessary value for keeping the currents at the desired ratio. I

In one form of this invention an amplifier metadyne supplies the field excitation of each motor. The amplifier metadyne includes a member'of its secondary variator winding traversed by a current equal or proportional to the current of the corresponding motor and inducing in the said motor a counter electromotive force opposing the said current.

In another form of the invention, dynamo electric machines known as Theta motor-metadynes replace conventional dynamos.

The metadyne here often mentioned is a direct current machine having more than twov brushes per cycle, the fiux created by the cur-. rent traversing the armature through a pair of brushes inducing an electromotive force between the brushes of another pair of same cycle.

The number of cycles of an electric machine is defined as the number of repetitions of the disposal of allelectric and mechanical'parts of the machine asfseen by an observeraccomplishe ing a complete circumference of the air gap.

The metadyne has'been described in many United States patents of the same inventor, see for instancaPatents Nos. 2,055,240; 1,987,417; 2,038,380; 2,049,389; 2,079,465; a more complete description has been given in Revue Generale d'e lElectricite, on March 8th and 15th, August 16th and 23rd, November 22nd and 29th and December 6th, 1930.

The armature currents of the metadyne are controlled by the ampere turns created by stator windings referred to as variator windings otthe metadyne.

The amplifier metadyne is a specific form 01' metadyne generating a current with an intensity equivalent-to a linear combination of given currents traversing the various members of a stator winding of the said metadyne, which is referred to as secondary variator winding. The amplifier metadyne is particularly described in the United States patent, 2,112,604.

The Theta motor metadyne is a dynamo electric machine described in the United States patent application, Serial No. 698,372, filed September- 20, 1946. Such a machine comprises essentially an armature having associated-therewith a commutator with a pair of primary brushes and a pair of secondary brushes displaced therefrom, the secondary brushes being short circuited, together with a stator winding having its magnetic axis coincident with the commutating axis of the primary brushes. The current traversing the short circuited secondary brushes excites the machine and induces a an electromotive force between the primary brushes. Such electromotive force is in opposition to the power current supplied to the machine and is proportional thereto. The stator winding is adapted to be energized for controlling the intensity of said power current.

The invention will be better understood withthe aid of the following description of some of its application, reference being made to the attached drawings.

Figure 1 shows a scheme of a transformermetadyne supplying current to two dynamos,

each of them being inserted in a different loop. Figure 2 shows the scheme of the same system, with dynamos excited by amplifier metadynes.

Figure 3 shows a scheme of a transformer meta dyne with Theta motor metadynes insertedin metadyneenergizing motors in two separate;

loops with variator windings connected in series.

3 Fig. 7 shows another form of metadyne energizing consumers in separate loops.

Figure 1 shows a transformer metadyne I having a set of primary brushes a, c and a set of secondary brushes b, displaced therefrom. The primary brushes a and c are connected to a source of direct current by terminals 6 and I. A motor 2 inserted in one loop of the metadyne is connected to thebrushes a and b. A motor 3 inserted the other loop is" connected to the brushes 6'' and d. order to cause the motors 2 and 3 to absorb the same power current, they are provided with series windings 24 and 25 re spectively; inducing in the respective armatures an electromotive force opposing the power current. When the motors must revolvein the op-- posite direction, the series windings must bereversed and for this purpose two reversing switches, 22 and 23 are provided. addition to the series windings, the motors 2, 3 are provided with windings 2t and 21 respectively.- The windings. 213 Bit may be separately excited-orshunt excited, providing for the control of the operation oi the motors;

According tothe present invention, as shown in Figure 2,; each ot the motors 2-, 3," is excited byasihglefield windin M,- respectively Each field winding is energized by separate amplifier metadynes ll, t9, whicharedriven by the metadyne shaft til-t The-amplifier metady ne" l-l su-pplies current to the field winding W of the: motor 2. The amplifier metadyne 19 supplies cur-- rent-to the'fieldwinding l5 oi the motor- 3. The secondary variator winding of the amplifier metady-ne H has members i3, i6. Themember L5 is separately excited by a source of current 3!: emails controlled. by rheostat- 32v The member 130i said variator winding is traversed by a fraction of the powercurrent of the-motor 2, imducing in the latter an electromotive forcev op posingthe power currer-i-t. The: amplifier metadyne 19 supplies current to the field winding [5- of the motor 3' and includes in its: secondary: variatorwinding a: member 28 and a member 21. Themember 21' creates in association with source of; current 3t a number ofampere turns controlledby a rheostat 34; The secondmember is=traversed by a fraction of the power current flowing through the: motor 3, inducing in: the lfatter'an electromotive force opposing the cur rent.

For reversing the direction of the empero turns created bythe coils I3 and 2G; small-switchgear 3-5 and 3s sufiice.v

The transformer metadyne referred: to abov is often. used in electric traction systems as shown in'Patent- No. 1,937,417,, Fig. 3 In order to: keep the current balanced in its two loops; great care must be taken toprovide ineach loop, motors-operating under the sameconditions and oiidentical construction.

Accordingatothe invention; Theta'motor-meta-= dynes are inserted in the loops. It is not then necessan to have the said Theta motor metadynes: operating under the same conditions,-. for instance-,:, at exactly the: same." speerci.

Eigure 3 there is shown atransformer metadycoe: 1', in one loopofwhich aT-h'eta motor metadyne 42 is inserted throughitsprimer-y" brushesa cf, while in the-cther loop another Theta motor metadyne- 43- is inserted throughits primary brushcs a, c". The currentf-absorbed by the Theta motor meta-dyne 2' is controlled by the *ampere' turns of its primary stator winding. throughthe-rheostat 51 inserted in the o 4 circuit of the source of current 50. The current absorbed by the motor 43 is controlled by the ampere turns of its primary stator winding through the rheostat 53 inserted inthe circuit of'the source of current 52. If an equal current in, each loop is desired, the operator-must balance equally the ampere turns in the windings 44 and 45 by suitable control of the rheostats 5i and 53.

4 snowe a scheme a S'ifigle Theta motor metadyne 42 inserted in dri 16015 of the mjetadyne I and with Theta motor metadynes 43 and 48 connected in parallel inserted in the other loop.- In order to obtain balanced ourrents in the two loops, it suffices to control primary stator windings 44, 45 and 49 of the respectiVe Theta motor metadynes so that the motor ineta'dynes" 43 and 48 absorb together the same current as the Theta motor metadyne 42. This example shows the utility of the present invention in the case of a locomotive equipped four motors which has one of its motors out of service. V

Figme 5 shows another example of the invention. ln one loop of atransformer metadyne l asingl'e Theta motor metadyne 43 is inserted while in the other loop are insertdtwo Theta" motor metadynes 42' and 48, of diiferent s'i'ie. Thus; a locomotive may be equipped with motors ofdifferent power whichmay be operated to absorb a current proportionalto their rated power. I

For the sake of simplicity the rheostats' and the sources of current applicable to the primary stator windings 44,-. 45 and 49 have not been shown irr figures 4 and 5.

The difference of current absorbed by two Theta-motor metadynes creates a supplementary current flowing betweenthe secondary short circuited brushes 2), dflrwhich in its turn induces an eleotromotive force between the primary brushes, a" cr of the Theta motor metadyne tending to equalize-the current absorbed by the primary brushes of the said-rnotors.

In orderto minimize the difference ofthecharacteristics' of the Theta motor Inetadyneand oi the transformer metadyne, the same controlling current may transverse the stator windings of the said-metadynes as shown Figs ure 6,; Accordinglythe current delivered by an auxiliary dynamo l-l-- traverses simultaneously seriesconnected: stator windings 44,- i0 and 45.

As shown lit-Figured, the current of the-trans former metadyne I is controlled by its secondary stator winding In; Inserted in the loops of metadyne l are? Theta motor metadynes" 42 and 43? The current of the motor metadynes 4.2 and- 43 is controlled by the ampere turns of primary stator windings 44 and 45 respectively; Current is supplied: to; the: series connected stator wind ings l' i; I13 andRSby means: 01 an auxiliary dy namo H. The dynamo H includes for example-a field' windirig 1c whims is shunt connected across the: bi ushcs b and c of the miner-archer meta: dyne i. Theauxiliary dynamo" is shown chanlcal-ly' coupled on the shaft IQ of the transformer'm'etauyne i as the latter generally ro tat'e's at aconstant speed.-

The' Theta; motor metadynes of the schemes considered above are traversed by currents? of" the sameintensityor by difi e'rerit current s ha't mega constant and or intensity; The operation isthesame'in both ca'ses;

transition of the Theta riiot'br meteoric from motoring? t2) regenerating? is obtained" slid ply by inverting the ampere turn or their primary stator windings, as indicated by the arrows in dotted lines, in Fig. 6. No modification whatever is needed of the circuits traversed by the power currents.

The invention herein described applies to any form of metadyne having more than one loop as shown in Figure 7 wherein the metadyne 6! has two loops in which the consumers 62 and 63 are inserted.

The transformer metadyne 6! includes brushes a, b, c, d, e and f and provides for two loops. The consumer 62 is inserted in one loop, being connected to the brushes b and f. The other consumer 63 is inserted in the other loop, connected to the brushes and e. The terminals 6 and l are connected to the remaining brushes 0. and d.

It will thus be seen that there is provided a plurality of direct current motors operating under voltages maintaining a given ratio and absorbing currents of a desired ratio of intensity and further means are provided for controlling these currents, in which the several objects of this invention are achieved.

As various possible embodiments might be made of the above described invention, and as various changes might be made in the embodimerits set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limited sense.

Having particularly described and ascertained the nature of my invention, and in what manner the same is to be performed, I declare that what I claim is:

1. In an electric system comprising a, plurality of dynamo machines operating under voltages maintained at a constant ratio, means for distributing the power current among the said imachines consisting in providing each of said machines with an excitation winding supplied with current by an amplifier metadyne, the intensity of said metadyne current being controlled by secondary stator windings of the said amplifier metaa dynes, one of the said stator windings being traversed by a current proportional to the power current of the corresponding dynamo and inclucing in the latter an electromotive force opposing the said power current.

2. In an electric system comprising 2. metadyne having a plurality of loops and a plurality of dynamos, each of said dynamos being inserted in different loops of said metadyne, means for distributing the power current among said dynamos consisting in providing an amplifier metadyne for supplying excitation current to the excitation winding of each of said dynamos, the intensity of said excitation current being controlled by secondary stator windings of said amplifier metadynes, one of the said stator windings being traversed by a. current proportional to the power current of the corresponding dynamo and inducing in the latter an electromotive force opposing the said power current.

3. An electric system comprising a plurality of dynamo electric machines, each machine including a pair of primary brushes, a pair of short circuited secondary brushes displaced therefrom and a stator winding having its magnetic axis coincident with the commutating axis of said primary brushes, dynamo electric means in circuit with the primary bushes of said machines for supplying power at voltages maintained at a constant ratio, and means for energizing each of said stator windings to provide a flux along the primary commutating axis of said machine, the flux due to the armature reaction of said machine along the primary commutating axis thereof creating an electromotive force opposing the power current, said fluxes being in aiding relation when said machines are motoring and being in opposed relation when said machines are regenerating.

4. An electric system comprising a transformer metadyne including a pair of primary brushes for connection to a source of direct current and a pair of secondary brushes displaced relative to said primary brushes, each of said primary brushes and one of said secondary brushes providing a loop, at least one dynamo electric machine connected in each of said loops, each dynamo electric machine comprising a pair of primary brushes for connection in the loop, a pair of short circuited secondary brushes displaced from said last mentioned pair of primary brushes, and a stator winding having its magnetic axis coincident with the commutating axis of said last mentioned primary brushes, and means for energizing said stator winding with a regulated current for controlling the intensity of the power current traversing said last mentioned primary brushes.

5. An electric system as in claim 4, wherein said transformer metadyne further includes a stator winding having its magnetic axis coincident with the commutating axis of the secondary brushes of said transformer metadyne, said last mentioned stator winding being connected in series with said first mentioned stator windmg.

6. In an electric system comprising a plurality of direct current machines, dynamo means having a plurality of outputs respectively in circuit with said machines for energizing said machines with voltages maintained at a constant ratio, means for distributing the power current among said machines comprising excitation means for each of said machines, each of said excitation means including a component for providing a. main exciting flux and a component for provid ing a corrective exciting flux for adjusting said main flux to a value proportional to said power current.

JOSEPH MAXIMUS PESTARINI.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,969,699 Pestarini Aug. 7, 1934 1,987,417 Pestarini June 8, 1935 2,049,389 Pestarini July 28, 1936 2,138,666 Pestarini Nov. 29, 1938 2,138,667 Pestarini Nov. 29, 1938 2,282,874 Moore May 12, 1942 FOREIGN PATENTS Number Country Date 16,510 France Dec. 10, 1912 

